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We develop a hierarchy of semilattice bases (S-bases) for frames. For a given (unbounded) meet-semilattice A, we analyze the interval in the coframe of sublocales of the frame of downsets of A formed by all frames with the S-base A. We study various degrees of completeness of A, which generalize the concepts of extremally disconnected and basically disconnected frames. We introduce the concepts of D-bases and L-bases, as well as their bounded counterparts, and show how our results specialize and sharpen in these cases. Classic examples that are covered by our approach include zero-dimensional, completely regular, and coherent frames, allowing us to provide a new perspective on these well-studied classes of frames, as well as their spatial counterparts. [ABSTRACT FROM AUTHOR]

The challenging endeavour of text-to-video creation requires transforming text descriptions into realistic and cohesive videos. This field of study has made substantial progress in recent years, with the development of diffusion models and generative adversarial networks (GANs). This study examines the most modern text-to-video generation models, as well as the various steps involved in text-to-video generation,including temporal coherence, video generation, and text encoding. We additionally emphasise the challenges involved with text-to-video generation, as well as recent advances to overcome these issues. The most frequently used datasets and metrics in this field are also analysed and reviewed [JJCIT 2024; 10(2.000): 198-213]

This paper summarizes over 60 years of radar system development at MIT Lincoln Laboratory, from early research on satellite tracking and planetary radar to the present ability to perform the centimeter-resolution imaging of resident space objects and future plans to extend this capability to geosynchronous range. [ABSTRACT FROM AUTHOR]

Dance Coherent Action Generation is a popular research task in recent years to generate movements and actions for computer-generated characters in a simulated environment. It is sometimes referred to as "Motion Synthesis". Motion synthesis algorithms are used to generate physically believable, visually compelling, and contextually appropriate movement using motion sensors. The Dance Coherent Action Generation Model (DCAM) is a generative framework for producing aesthetically pleasing movements using deep learning from small amounts of data. By learning an internal representation of motion dynamics, DCAM can synthesize long sequences of movements in which coherent patterns can be created through latent space interpolation. This framework provides a mechanism for varying the amplitude of the generated motion, allowing further realistic thinking and expression. The proposed model obtained 93.79% accuracy, 93.79% precision, 97.75% recall and 92.92% F1 score. DCAM exploits the balance between imitation and creativity by enabling the production of novel outputs from limited input data and can be trained in an unsupervised manner or fine-tuned with sparse supervision. Furthermore, the framework is easily extended to handle multiple layers of abstraction and can be further personalized to a particular type of movement, enabling the generation of highly individualized outputs. [ABSTRACT FROM AUTHOR]

The nonlinear optical susceptibilities are analyzed in their optical propagation length considering the incoherent-coherent contributions with the dependence on the relaxation times. In addition, some symmetry properties of the Four-Wave mixing (FWM) signal concerning the frequency detuning exchange are used in the study, without restricting ourselves to the maxima of population oscillations. We analyze the behaviors of these optical responses in a vibronic coupling scheme using a molecule model consisting of two coupled harmonic curves of electronic energies with displaced minima in position and nuclear energies. The solvent effect in our model is treated through the natural Bohr frequency shift to a time-dependent function, with explicit manifestations in its comparison as if the upper state were broadened. Our results for both FWM signal propagation and nonlinear optical susceptibilities are sensitive to the intramolecular coupling parameters, solvent stochasticity, and perturbation order for the treatment of the weak probe beam. The consideration of a second-order probe beam in FWM would not represent a significant contribution to the predicted results, since its percentage contribution is negligible within the model development framework; however, this contribution becomes important when increasing the ratio between longitudinal and transverse relaxation times.

P-band radiometry has been demonstrated to have a deeper sensing depth than L-band, making the consideration of multilayer microwave interactions necessary. In addition, the scattering and phase interference effects are different at the P-band, requiring a reconsideration of the need for coherent models. However, the impact remains to be clarified, and understanding the validity and limitations of these models at both L- and P-bands is crucial for their refinement and application. Therefore, two general categories of microwave emission models, including two stratified coherent models (Njoku and Wilhite) and four incoherent models (conventional tau-omega model and three multilayer models being zero-order, first-order, and incoherent solution), were intercompared for the first time on the same dataset. This evaluation utilized observations of L- and P-bands radiometry under different land cover conditions from a tower-based experiment in Victoria, Australia. Model estimations of brightness temperature (TB) were consistent with measurements, with the lowest root mean square error (RMSE) at P-band V-polarization under corn (2 K) and the highest RMSE at L-band H-polarization under bare soil (13 K). Coherent models performed slightly better than incoherent models under bare soil (3 K less RMSE), while the opposite was true under vegetated soil conditions (1 K less RMSE). Coherent and incoherent models showed maximum differences (3 K at P-band and 2 K at L-band), correlating strongly with soil moisture variations at 0–10 cm. Findings suggest that coherent and incoherent models performed similarly; thus, incoherent models may be preferable for estimating TB at L- and P-bands due to reduced computational complexity.

P-band radiometry has been demonstrated to have a deeper sensing depth than L-band, making the consideration of multilayer microwave interactions necessary. In addition, the scattering and phase interference effects are different at the P-band, requiring a reconsideration of the need for coherent models. However, the impact remains to be clarified, and understanding the validity and limitations of these models at both L- and P-bands is crucial for their refinement and application. Therefore, two general categories of microwave emission models, including two stratified coherent models (Njoku and Wilhite) and four incoherent models (conventional tau-omega model and three multilayer models being zero-order, first-order, and incoherent solution), were intercompared for the first time on the same dataset. This evaluation utilized observations of L- and P-bands radiometry under different land cover conditions from a tower-based experiment in Victoria, Australia. Model estimations of brightness temperature (TB) were consistent with measurements, with the lowest root mean square error (RMSE) at P-band V-polarization under corn (2 K) and the highest RMSE at L-band H-polarization under bare soil (13 K). Coherent models performed slightly better than incoherent models under bare soil (3 K less RMSE), while the opposite was true under vegetated soil conditions (1 K less RMSE). Coherent and incoherent models showed maximum differences (3 K at P-band and 2 K at L-band), correlating strongly with soil moisture variations at 0–10 cm. Findings suggest that coherent and incoherent models performed similarly; thus, incoherent models may be preferable for estimating TB at L- and P-bands due to reduced computational complexity. [ABSTRACT FROM AUTHOR]

Forecast reconciliation of multivariate time series maps a set of incoherent forecasts into coherent forecasts to satisfy a given set of linear constraints. Available methods in the literature either follow a projection matrix-based approach or an empirical copula-based reordering approach to revise the incoherent future sample paths to obtain reconciled probabilistic forecasts. The projection matrices are estimated either by optimizing a scoring rule such as energy or variogram score or simply using a projection matrix derived for point forecast reconciliation. This article proves that (a) if the incoherent predictive distribution is jointly Gaussian, then MinT (minimum trace) minimizes the logarithmic scoring rule for the hierarchy; and (b) the logarithmic score of MinT for each marginal predictive density is smaller than that of OLS (ordinary least squares). We illustrate these theoretical results using a set of simulation studies and the Australian domestic tourism dataset. The estimation of MinT needs to estimate the covariance matrix of the base forecast errors. We have evaluated the performance using the sample covariance matrix and shrinkage estimator. It was observed that the theoretical properties noted above are greatly impacted by the covariance matrix used and highlighted the importance of estimating it reliably, especially with high dimensional data. [ABSTRACT FROM AUTHOR]

Optical transmission impairments are most critical reason to reduce both capacity and achievable transmission distance in optical communication system. Advanced modulation formats are important keys to reduce optical transmission impairments in digital signal processing (DSP) based coherent wavelength division multiplexed (WDM) system. These formats are more robust to non-linearity of optical fiber and results in increasing both spectral efficiency and bandwidth. Coherent detection technique increases sensitivity of receiver up to 30 dB in comparison of direct detection. Simulink seems to be the best cost-effective platform for analyzing mathematical modeling of optical coherent system. In this paper, mathematical model has been developed to analyze the optical transmission impairments by employing the advanced polarization multiplexed QPSK modulation in DSP based WDM coherent system. The simulation results have shown bit error rate (BER) improvement up to 10−6 and enhanced transmission distance to 150 km. These values have seen to be in close proximity with experimental results. The developed mathematical model seems to be more useful for extending the existing WDM optical system for longer distances with acceptable BER. [ABSTRACT FROM AUTHOR]

Let MM be a right RR-module with S=End(MR)S={\rm{End}}\left({M}_{R}). Given two cardinal numbers α\alpha and β\beta and a row-finite matrix A∈RFMβ×α(S)A\in {{\rm{RFM}}}_{\beta \times \alpha }\left(S), SM{}_{S}M is called injective relative to AA if every left SS-homomorphism from S(β)A{S}^{\left(\beta )}A to MM extends to one from S(α){S}^{\left(\alpha )} to MM. It is shown that SM{}_{S}M is injective relative to AA if and only if the right RR-module Mβ∕AMα{M}^{\beta }/A{M}^{\alpha } is cogenerated by MM. SS is called left coherent relative to A∈Sβ×αA\in {S}^{\beta \times \alpha } if Ker(S(β)S→S(β)SA)\left({}_{S}S^{\left(\beta )}\to {}_{S}S^{\left(\beta )}A) is finitely generated. It is shown that SS is left coherent relative to AA if and only if Mn∕AMα{M}^{n}/A{M}^{\alpha } has an add(M){\rm{add}}\left(M)-preenvelope. As applications, we obtain the necessary and sufficient conditions under which Mn∕AMα{M}^{n}/A{M}^{\alpha } has an add(M){\rm{add}}\left(M)-preenvelope, which is monic (resp., epic, having the unique mapping property). New characterizations of left nn-semihereditary rings and von Neumann regular rings are given.

Tujuan kegiatan untuk melatih pelaku UMKM dalam berkomunikasi tulis formal seperti bersurat kedinasan melalui pelatihan berbasis digital. Salah satu cara untuk meningkatkan kompetensi individual dan menguatkan karakteristik individu dalam kompetensi komukasi dan penguasaan literasi digital untuk menunjang kinerja usahanya. Salah satu kinerja usaha pelaku UMKM adalah kemampuan komunikasi tulis dalam kegiatan persuratan, perijinan, dan proposal. Pembinaan yang diperlukan tentunya dalam bentuk pelatihan yang lebih intensif dan berkesinambungan. Pembinaan dimaksud adalah pelatihan yang berkenaan dengan kemampuan berbahasa tulis melalui persuratan, perijinan, dan bentuk proposal menggunakan sarana digital, yang dibatasi pada pelaku UMKM di kelurahan Bahagia, Babelan, Bekasi. Metode yang akan dilakukan dalam pelaksanaan program ini melalui daring dan luring dalam empat tahapan, yaitu: 1) pemaparan mengenai pentingnya kemampuan keterampilan berbahasa tulis untuk mencapai tujuan komunikasi bahasa, 2) pembahasan mengenai berbagai kaidah bahasa yang kohesif dan koheren, 3) para pelaku UMKM melakukan praktek berbahasa tulis menyusun surat sesuai konteks kedinasan dan bidang usaha melaui kegiatan menyunting untuk tujuan memperbaiki maksud tujuan komunikasi bahasa surat, 4) kegiatan pendampingan dan refleksi praktek bersurat dan berbahasa yang koheren dan kohesif secara luring.

One common method to improve the low signal‐to‐noise ratio of the photoacoustic (PA) signal generated from weak absorbers or absorbers located in deep tissue is to acquire signal multiple times from the same region and perform averaging. However, pulse‐to‐pulse laser fluctuations together with differences in the beam profile of the pulses create undeterministic multiple scattering processes in the tissue. This phenomenon consequently induces a spatiotemporal displacement in the PA signal samples which in turn deteriorates the effectiveness of signal averaging. Here, we present an adaptive coherent weighted averaging algorithm to adjust the locations and values of PA signal samples for more efficient signal averaging. The proposed method is evaluated in a linear array‐based PA imaging setup of ex vivo sheep brain. [ABSTRACT FROM AUTHOR]

We examine the cross-shelf variation of internal tides (ITs) west of the Dongsha Plateau in the northern South China Sea based on observations from 4 moorings deployed between August 2017 and September 2018. On the slope, the amplitude of diurnal baroclinic current ellipses are 5 times larger than that of barotropic currents. The baroclinic energy quickly dissipates during cross-shelf propagation, and barotropic currents become dominant on the shelf outside of the Zhujiang River Estuary, with the amplitude of semidiurnal barotropic current ellipses being 10 times larger than that of the baroclinic ones. Dynamic modal decomposition indicates the first baroclinic mode is dominant for both diurnal and semidiurnal ITs. The total horizontal kinetic energy (HKE) of the first three baroclinic modes shows spatiotemporal differences among the 4 moorings. On the slope, the HKE for diurnal ITs is stronger in summer and winter, but weaker in spring and autumn; for semidiurnal ITs there is a similar seasonal variation, but the HKE in winter is even stronger than that in summer. On the shallow shelf, both diurnal and semidiurnal ITs maintain a certain intensity in summer but almost disappear in winter. Further analysis shows that only the upper water column is affected by seasonal variation of stratification on the slope, variation of diurnal ITs is thus controlled by the semi-annual cycle of barotropic energy input from the Luzon Strait, while the incoherent baroclinic currents make a major contribution to the temporal variation of semidiurnal ITs. For the shelf region, the water column is well mixed in winter, and the baroclinic energy largely dissipates when ITs propagate to the shelf zone despite of a strong barotropic energy input from the Luzon Strait. [ABSTRACT FROM AUTHOR]

Let $ N $ be a left $ R $-module with the endomorphism ring $ S = \text{End}(_{R}N) $. Given two cardinal numbers $ \alpha $ and $ \beta $ and a matrix $ A\in S^{\beta\times\alpha} $, $ N $ is called flat relative to $ A $ in case, for each $ x\in l_{N^{(\beta)}}(A) = \{u\in N^{(\beta)} \mid uA = 0\} $, there are a positive integer $ k $, $ y\in N^{k} $ and a $ k\times \beta $ row-finite matrix $ C $ over $ S $ such that $ CA = 0 $ and $ x = yC $. It is shown that $ N_{S} $ is flat relative to a matrix $ A $ if and only if $ l_{N^{(\beta)}}(A) $ is generated by $ N $. $ S $ is called left coherent relative to $ A $ if Ker$ (_{S}S^{(\beta)}\to _{S}S^{(\beta)}A) $ is finitely generated. It is shown that $ S $ is left coherent relative to $ A $ if and only if Hom$ _{R}(N, l_{N^{n}}(A)) $ is a finitely generated left $ S $-module if and only if $ l_{N^{n}}(A) $ has an add$ (N) $-precover (add$ (N) $ denotes the category of all direct summands of finite direct sums of copies of $ _{R}N $). Regarding applications, new necessary and sufficient conditions for epic (monic, having the unique mapping property) add$ (N) $-precovers of $ l_{N^{(\beta)}}(A) $ are investigated. Also, some new characterizations of left $ n $-semihereditary rings and von Neumann regular rings are given.

This paper summarizes over 60 years of radar system development at MIT Lincoln Laboratory, from early research on satellite tracking and planetary radar to the present ability to perform the centimeter-resolution imaging of resident space objects and future plans to extend this capability to geosynchronous range.

In recent years, researchers have tried to estimate the direction-of-arrival (DOA) of wideband sources and several novel techniques have been proposed. In this paper, we compare six algorithms for calculating the DOA of broadband signals, namely coherent subspace signal method (CSSM), two-sided correlation transformation (TCT), incoherent multiple signal classification (IMUSIC), test of orthogonality of frequency subspaces (TOFS), test of orthogonality of projected subspaces (TOPS), and squared TOPS (S-TOPS). The comparison is made through computer simulations for different parameters, such as signal-to-noise ratio (SNR), in order to establish the efficiency and performance of the discussed methods in noisy environments. CSSM and TCT require initial values, but the remaining approaches do not need any preprocessing.

In recent years, researchers have tried to estimate the direction-of-arrival (DOA) of wideband sources and several novel techniques have been proposed. In this paper, we compare six algorithms for calculating theDOAof broadband signals, namely coherent subspace signal method (CSSM), two-sided correlation transformation (TCT), incoherent multiple signal classification (IMUSIC), test of orthogonality of frequency subspaces (TOFS), test of orthogonality of projected subspaces (TOPS), and squared TOPS (S-TOPS). The comparison is made through computer simulations for different parameters, such as signal-to-noise ratio (SNR), in order to establish the efficiency and performance of the discussed methods in noisy environments. CSSM and TCT require initial values, but the remaining approaches do not need any preprocessing. [ABSTRACT FROM AUTHOR]

We extend several results of Helfer, Wise, Louder and Wilton related to coherence in one-relator groups to the more general setting of one-relator products of locally indicable groups. The methods developed to do so also give rise to a new proof of a theorem of Brodskiĭ. [ABSTRACT FROM AUTHOR]

Let be a left -module with the endomorphism ring . Given two cardinal numbers and and a matrix , is called flat relative to in case, for each , there are a positive integer , and a row-finite matrix over such that and . It is shown that is flat relative to a matrix if and only if is generated by . is called left coherent relative to if Ker is finitely generated. It is shown that is left coherent relative to if and only if Hom is a finitely generated left -module if and only if has an add -precover (add denotes the category of all direct summands of finite direct sums of copies of ). Regarding applications, new necessary and sufficient conditions for epic (monic, having the unique mapping property) add -precovers of are investigated. Also, some new characterizations of left -semihereditary rings and von Neumann regular rings are given. [ABSTRACT FROM AUTHOR]

The traditional ultrasonic dynamic focusing imaging which simply uses the delay-and-sum method in beamforming shows low resolution and poor contrast. In this study, based on the coherent pixel-based beamforming (Coherent PB), a novel Wiener pre-filter with high computational efficiency is applied to correct the phase of the entire array signal by using the pulse-echo at the focal point. We also apply a Wiener post-filter calculating adaptive weights for the beamforming results of each sub-aperture to suppress the noise and artifacts. The proposed method's effectiveness is verified through simulation experiments, phantom experiments, and in vivo experiments. Compared with Coherent PB, the proposed method significantly improves the axial resolution and contrast of images while maintaining the high lateral resolution and computational efficiency, which shows certain clinical application value.

It has been shown that Relative Humidity (RH) provokes dimensional displacement detectable directly from surfaces using holographic interferometry. RH variations constitute a physical environmental load that drives organic materials to a constant equilibrium cycle. This paper is a small synopsis of the interferometric research direction and a data acquisition on the detection of the dimensional impact of relative humidity on cultural heritage objects. Since RH cycling is unavoidable, the interferometric data change depends on the object structure and RH cycle characteristics. Based on the fact that each artwork is by construction unique, and on the observation that the effects of an RH cycle on the structural condition of any artwork are also unique but the preventive conservation strategies require generalised approaches and not on a case-by-case study, being introduced is a novel, universal, preventive deterioration methodology: “deformation threshold value” (DTV). DTV is assignable to each distinct object in order to control routinely its structural condition and prevent damage. DTV is not assigned hypothetically based on any assumed/expected reactions but from a monitored calibration of the artwork in its environment. Each artwork in its hosted environment has its unique reaction. The reaction, though, is not steady but changes as the artwork changes. DTV can be acquired routinely and valued accordingly to seasonal RH change. Monitoring the seasonal RH and seasonal dimensional reaction has been shown to correspond to a standard DTV pattern whose deviations violate the expected seasonal reaction. Through the interferometric monitoring of surface, the distinct DTV acts as a safeguard for the artwork. In this synopsis, some results of the generation of DTVs are shown. Our future plan is for the DTV numbers to serve as data inputs for preventive models to formulate a distinct risk index representative of each artwork condition and to be used as remote risk warning to prevent its deterioration. Based on the DTV concept, methods and instruments for sequential data acquisition aim to present experimental data outputs as DTVs that identify transient shape changes prior to visible damage have been developed. In this research, the starting point was the interferometric quantification of the displacement of well-characterized fresh samples. The fresh samples are known in terms of density, cut, thickness, moisture content, structural condition and are submitted to RH simulation cycles. Shown here are three exemplary cases: usual, abrupt and smooth. The interferometric monitoring following the cycles of RH is a long-term duration of several weeks; measurements are performed directly from the surface, and relative displacement (RD) from temporal measurements of interference fringes provide the required output data to calculate the rate of displacement (RoD) of the surface. Measuring the impact of RH directly from the artwork surface allows the detection of the temporal diversity of structural reactions to the same RH cycle for distinct artworks. The monitoring system uses interferometric precision provided by digital holographic speckle-pattern interferometry (DHSPI) placed on a specially designed climate chamber DHSPI monitoring workstation.

It has been shown that Relative Humidity (RH) provokes dimensional displacement detectable directly from surfaces using holographic interferometry. RH variations constitute a physical environmental load that drives organic materials to a constant equilibrium cycle. This paper is a small synopsis of the interferometric research direction and a data acquisition on the detection of the dimensional impact of relative humidity on cultural heritage objects. Since RH cycling is unavoidable, the interferometric data change depends on the object structure and RH cycle characteristics. Based on the fact that each artwork is by construction unique, and on the observation that the effects of an RH cycle on the structural condition of any artwork are also unique but the preventive conservation strategies require generalised approaches and not on a case-by-case study, being introduced is a novel, universal, preventive deterioration methodology: "deformation threshold value" (DTV). DTV is assignable to each distinct object in order to control routinely its structural condition and prevent damage. DTV is not assigned hypothetically based on any assumed/expected reactions but from a monitored calibration of the artwork in its environment. Each artwork in its hosted environment has its unique reaction. The reaction, though, is not steady but changes as the artwork changes. DTV can be acquired routinely and valued accordingly to seasonal RH change. Monitoring the seasonal RH and seasonal dimensional reaction has been shown to correspond to a standard DTV pattern whose deviations violate the expected seasonal reaction. Through the interferometric monitoring of surface, the distinct DTV acts as a safeguard for the artwork. In this synopsis, some results of the generation of DTVs are shown. Our future plan is for the DTV numbers to serve as data inputs for preventive models to formulate a distinct risk index representative of each artwork condition and to be used as remote risk warning to prevent its deterioration. Based on the DTV concept, methods and instruments for sequential data acquisition aim to present experimental data outputs as DTVs that identify transient shape changes prior to visible damage have been developed. In this research, the starting point was the interferometric quantification of the displacement of well-characterized fresh samples. The fresh samples are known in terms of density, cut, thickness, moisture content, structural condition and are submitted to RH simulation cycles. Shown here are three exemplary cases: usual, abrupt and smooth. The interferometric monitoring following the cycles of RH is a long-term duration of several weeks; measurements are performed directly from the surface, and relative displacement (RD) from temporal measurements of interference fringes provide the required output data to calculate the rate of displacement (RoD) of the surface. Measuring the impact of RH directly from the artwork surface allows the detection of the temporal diversity of structural reactions to the same RH cycle for distinct artworks. The monitoring system uses interferometric precision provided by digital holographic speckle-pattern interferometry (DHSPI) placed on a specially designed climate chamber DHSPI monitoring workstation. [ABSTRACT FROM AUTHOR]

This paper investigates the performance analysis of RS-coded and un-coded coherent M-QAM modulated OFDM free space optical communication system. The system performance is analyzed using block error rate. Mathematical expressions are derived for the average block error rate under the combined effects of attenuation loss, pointing error, and gamma-gamma distributed atmospheric turbulence, and results are validated using Monte Carlo simulation. M-QAM modulated OFDM system with RS codes enhances the system performance more than an un-coded system. Coherent OFDM-FSO improves the system performance by overcoming the effects of atmospheric factors. [ABSTRACT FROM AUTHOR]

Coherent scatter echoes from disintegrating meteors and from the unstable ionospheric E‐region can overlap considerably between 90 and 110 km altitudes. As the physical origin of plasma irregularities produced by meteor trails differs starkly from that of E‐region auroral irregularities, this has consequences for winds as well as electrodynamic studies, thereby introducing a need to distinguish between the two types of echoes. To that goal, we have developed a novel separation algorithm to automatically sort through arbitrarily large data sets in the region of overlap. This proves very useful when the 3D location of echoes is available. The algorithm uses a definition of crowding, or clustering, in both time and space and has been developed and tested with a comprehensive data set obtained from the recently built Canadian icebear 3D radar. We discuss the characteristics belonging to the two classes of echoes, and present statistical results about the location of each type of echo as a function of conditions. Our proposed algorithm can be applied to any coherent scatter echo data with high resolution 3D location information. Plain Language Summary: Radars measure turbulence in space plasma by bouncing a signal off of sharp plasma density gradients in the ionosphere. For decades, such coherent radars have been useful tools to investigate the ionosphere. However, when probing E‐region plasma, a coherent radar will pick up plasma produced by meteors as they enter Earth's atmosphere. We have developed an automatic algorithm to separate meteor trail echoes, as they are called, from space plasma measurements. We demonstrate the efficiency of this algorithm on the icebear 3D data set, which has an unprecedented resolution, and offers accurate 3D location data for space plasma turbulence. Key Points: Using new data from icebear 3D, we find that ionospheric turbulence overlap with meteor trail echoes between 90 and 110 km altitudeThe starkly different patterns of clustering in time and space of high latitude ionospheric turbulence and meteoric echoes are used to distinguish the echo typesThe spatial and temporal separation between observed meteor trail echoes is normally several orders of magnitude above that of ionospheric turbulence echoes at high latitudes [ABSTRACT FROM AUTHOR]

This paper describes the energy-efficient realization of a QPSK optical receiver (CoRX) for short-reach intra-datacenter interconnects based on analog coherent detection. The CoRX comprises inphase and quadrature channels for each polarization and a high-speed phase-frequency detector (PFD) that provides feedback to stabilize an optical local oscillator (LO) and maintain coherence with the received optical signal. Each receive (RX) channel consists of a transimpedance amplifier (TIA) based on a Cherry-Hooper emitter follower (CHEF). The electronic RX is implemented in a 130-nm SiGe HBT technology ( $f_{T} = 300$ GHz), consumes 534 mW of DC power for a total electrical RX energy efficiency of 5.34 pJ/bit, and occupies 2.8 $mm^{2}$ . Electrical characterization of the CoRX on an FR-4 PCB assembly demonstrates operation up to 60 GBaud with a bit error rate (BER) of less than 10−12. A co-packaged optical/electrical CoRX assembly with a silicon photonic receiver is characterized using a commercial-off-the-shelf quadrature phase-shift keying (QPSK) transmitter for constellations up to 50 GBaud (100 Gbps) at BER below KP4-FEC ( $2.2\times 10^{-4}$ ).

The step-index heavily germanium-doped silica fibers with all normal dispersion (ANDi) are promising candidates for highly coherent supercontinuum (SC). These ANDi step-index silica fibers are easier to fabricate, splice and handle than silica photonic crystal fibers (PCFs). 40% GeO2 doped step-index silica fiber of 3 μm core diameter has flat and near-zero dispersion which is between −5.5 and 0 ps/nm/km from 1.4 to 2.4 μm. Highly coherent SC spanning from 1050 nm to 2100 nm generated from the ANDi step-index heavily germanium-doped silica fiber pumped at 1560 nm. All-fiber coherent SC source from 1200 nm to 2200 nm is achieved by splicing the ANDi silica fiber with a 1560 nm femtosecond fiber laser of 90% couple efficiency. Moreover, the step-index ANDi germania-core silica fiber of 2.2 μm core diameter is proposed to generate coherent mid-infrared SC from 1.7 to 3 μm. The ANDi step-index silica fibers not only can generate highly coherent broadband SC at near infrared or mid-infrared region but also can easily achieve all-fiber structure coherent SC source. And the experiment of supercontinuum generation in UNNA4 and UHNA7 fibers with different pump wavelengths indicates that the pump of 1064 nm is not suitable for coherent supercontinuum generation in the fiber of UNNA4 and UHNA7.

Biomedical data preprocessing and efficient computing can be as important as the statistical methods used to fit the data; data processing needs to consider application scenarios, data acquisition and individual rights and interests. We review common principles, knowledge and methods of integrated research according to the whole-pipeline processing mechanism diverse, coherent, sharing, auditable and ecological. First, neuromorphic and native algorithms integrate diverse datasets, providing linear scalability and high visualization. Second, the choice mechanism of different preprocessing, analysis and transaction methods from raw to neuromorphic was summarized on the node and coordinator platforms. Third, combination of node, network, cloud, edge, swarm and graph builds an ecosystem of cohort integrated research and clinical diagnosis and treatment. Looking forward, it is vital to simultaneously combine deep computing, mass data storage and massively parallel communication. [ABSTRACT FROM AUTHOR]

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In this paper, by mapping datasets to a set of non-linear coherent states, the process of encoding inputs in quantum states as a non-linear feature map is re-interpreted. As a result of the fact that the radial basis function is recovered when data is mapped to a complex Hilbert state represented by coherent states, non-linear coherent states can be considered as a natural generalisation of the associated kernels. In this paper, as an example of kernels based on non-linear coherent states, we propose kernel functions based on generalized hypergeometric functions, as orthogonal polynomial functions. The suggested kernel is implemented with the support vector machine (SVM) on two well known datasets (make_circles, and make_moons) and outperforms the baselines, even when the level of noise is high. In addition, we study the impact of the geometrical properties of the feature space, obtained by the non-linear coherent states, on the SVM classification task, by considering the Fubiniâ€"Study metric of the associated coherent states. [ABSTRACT FROM AUTHOR]

This article presents a pulsed-coherent lidar that uses a 19-GHz pulse-modulated optical carrier and segmented time-of-flight (ToF) detection. The receiver analog frontend (AFE) employs a down-conversion chain that consists of a phase-invariant programmable-gain low-noise amplifier (PI-PGLNA), a sub-harmonic mixer (SHM), and an inverter-based phase-invariant programmable-gain amplifier (PI-PGA). The local oscillator (LO) is generated from a phase-locked loop (PLL) with a ring-type voltage-controlled oscillator (VCO). An analog-to-digital converter (ADC) subsamples the down-converted signal, and a digital signal processor (DSP) calculates the coarse, intermediate, and fine ToF. At the receiver input, a narrowband matching is implemented between the p-i-n photodiode and the PI-PGLNA with direct wire bonding. The system achieves 6- $\mu \text{m}$ precision with a 5-MSa/s sampling rate at a 2.5-m distance. The 2-D scanning is achieved with this lidar with the use of an MEMS mirror. [ABSTRACT FROM AUTHOR]

Direction of arrival (DOA) estimation of coherent sources with a uniform circular array (UCA) is an intractable problem. The method-of-direction-estimation (MODE) algorithm has strong superiority in handling coherent sources compared with the classical MUSIC, and ESPRIT algorithms. However, MODE is sensitive to source numbers and does not work well in the UCA scenario. In order to improve the performance of MODE, a robust DOA estimation method named UCA-PUMA (principal-eigenvector-utilization for- modal-analysis) is proposed. The complicated non-Vandermonde structured steering vector of UCA is transformed into a virtual Vandermonde structured steering vector in mode space. The proposed method gives a closed-form solution compared with the original UCA-MODE algorithm. The performance of the UCA-PUMA method is evaluated by simulations. Simulation results demonstrate that the UCA-PUMA is more robust to source numbers than the UCA-MODE, and coherent sources can be handled without spatial smoothing. In addition, the UCA-PUMA fully takes advantage of the UCA, which is able to discriminate sources coming from a 360° azimuthal field of view. [ABSTRACT FROM AUTHOR]

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We report the simulations of coherent supercontinuum generation from 2.63 to 8.04 μm in a silicon germanium photonic waveguide. The influence of input quantum noise pulses on coherence of the generated spectra was investigated. A high value of first order degree of coherence (i.e. 0.98) on supercontinuum spectra was predicted numerically. Our mid-infrared simulated coherent chirped supercontinuum source was then used as the input light source in absorption spectroscopy of carbon dioxide and methane gases. The simulated absorbance spectra for these greenhouse gases have high molecular contrast, thanks to the intense, chirped supercontinuum used. [Display omitted] • Supercontinuum generation from 2.63 to 8.04 μm in a silicon germanium waveguide was simulated. • The first order degree of coherence for supercontinuum spectra at 2.13 kW peak power was calculated. • Mid-infrared absorption spectra for carbon dioxide and methane gases were simulated. • The absorbance spectra of CO 2 and CH 4 gases exhibit high molecular contrast due to the chirped supercontinuum employed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nonlinear optical responses in four-wave mixing. • Propagation effects and intramolecular couplings in two-state systems. • Coherent and incoherent responses in the net absorption measure. • Solvent effects on nonlinear optical responses. • Stochasticity and vibronic couplings in the absorptive properties of a two-state system. The nonlinear optical susceptibilities are analyzed in their optical propagation length considering the incoherent-coherent contributions with the dependence on the relaxation times. In addition, some symmetry properties of the Four-Wave mixing (FWM) signal concerning the frequency detuning exchange are used in the study, without restricting ourselves to the maxima of population oscillations. We analyze the behaviors of these optical responses in a vibronic coupling scheme using a molecule model consisting of two coupled harmonic curves of electronic energies with displaced minima in position and nuclear energies. The solvent effect in our model is treated through the natural Bohr frequency shift to a time-dependent function, with explicit manifestations in its comparison as if the upper state were broadened. Our results for both FWM signal propagation and nonlinear optical susceptibilities are sensitive to the intramolecular coupling parameters, solvent stochasticity, and perturbation order for the treatment of the weak probe beam. The consideration of a second-order probe beam in FWM would not represent a significant contribution to the predicted results, since its percentage contribution is negligible within the model development framework; however, this contribution becomes important when increasing the ratio between longitudinal and transverse relaxation times. [ABSTRACT FROM AUTHOR]

Our main result states that if G is a finitely generated soluble group having a normal Abelian subgroup A, such that G/A and are nilpotent (respectively, finite-by-nilpotent, periodic-by-nilpotent, nilpotent-by-finite, finite-by-supersoluble, supersoluble-by-finite) for all (x, a) ∈ G × A, then so is G. We deduce that if 픛 is a subgroup and quotient closed class of groups and if all 2-generated Abelian-by-cyclic groups of 픛 are nilpotent (respectively, finite-by-nilpotent, periodic-by-nilpotent, nilpotent-by-finite, finite-by-supersoluble, supersoluble-by-finite), then so are all finitely generated soluble groups of 픛. We give examples that show that our main result is not true for other classes of groups, like the classes of Abelian, supersoluble, and FC-groups. [ABSTRACT FROM AUTHOR]

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Different constraints to the neutrino electric millicharge (NEM) have been obtained by considering interactions such as the elastic neutrino-electron scattering (ENES). However, the great potential of the coherent elastic neutrino-nucleus scattering (CE NS) in future reactor neutrino experiments could be an alternative to improve the current limits on the NEM. In this work we study the sensitivity of ENES and CE NS interactions in reactor experiments to the neutrino charge through a combination of different experimental data. Bounds up to the order of are achieved from CE NS at reactor neutrino experiments. [ABSTRACT FROM AUTHOR]